The spinal cord is divided into four segments: cervical, thoracic, lumbar and
sacral. Together, they make up a vital part of the body's central processing
nervous system; injury to the spinal cord can be grave and sometimes fatal. The
cervical part of the spinal cord lies in the neck. Injuries occurring at the
second cervical vertebrae, known as C2, manifest through a particular
constellation of symptoms and signs.
As stated by the University of Alabama at Birmingham Spinal Cord Injury
Information Network, an injury in the upper cervical region of the spinal
cord—vertebrae C1 through C3—will cause complete paralysis of breathing muscles.
This occurs because all the nerve signals sent by the brain originate at a
higher level. An injury at C2 will interrupt the nervous system's signals to the
muscles responsible for breathing. The muscles paralyzed by such an injury
include the diaphragm, the chest and abdominal muscles, and the neck muscles. If
the injury is complete and the spinal cord is completely transected at this
level, the patient will lose the ability to breathe spontaneously and will need
a ventilator.
The Merck Manuals Online Medical Library notes that injury of the spinal cord
at C2 will result in complete or partial paralysis of all four limbs and trunk
muscles. The muscles comprising the anal and bladder sphincters are also
paralyzed causing the patient to lose voluntary control over urination and
defecation. If the spinal cord is severely injured, the patient could remain
paralyzed for life. If the injury is partial, however, the patient may regain
some movement, particularly of the trunk muscles.
The nerves responsible for delivering sensation also pass through the spinal
cord. Each spinal cord segment gives sensory supply to an area of the skin
called a dermatome. All sensations are relayed to the brain via the spinal cord
in order to provide feeling.
According to the American Spinal Injury Association, C2 provides sensory
supply to the area over the back of the head and the top part of the neck.
Injury at the C2 level will cause the patient to be totally deprived of
sensations below that level because of the interruption of the pain pathway and
the nerve signals going to the brain.
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